**Core Concept**
Streptococcus faecalis, also known as Enterococcus faecalis, is a gram-positive, facultative anaerobic bacterium that exhibits unique characteristics that distinguish it from other streptococci. Its ability to grow in environments with high salt concentrations is a key feature that has implications for its identification and pathogenicity.

**Why the Correct Answer is Right**
Streptococcus faecalis is able to grow in 6.5% NaCl solution due to its ability to accumulate compatible solutes, such as potassium ions and glutamate, which help maintain osmotic balance and allow the cell to survive in high-salt environments. This adaptation is essential for its survival in various niches, including the human gut and soil. The ability to grow in high-salt conditions is a characteristic feature used in the identification of E. faecalis.

**Why Each Wrong Option is Incorrect**
**Option B:** E. faecalis is not a lactose fermenter, and its ability to ferment lactose is not a reliable characteristic for its identification. In fact, E. faecalis is typically non-lactose fermenting.
**Option C:** E. faecalis is highly resistant to heat and can survive temperatures up to 60°C for 30 minutes, making it a concern in the sterilization of medical equipment.
**Option D:** While E. faecalis does have a cell wall, its classification is not based on the teichoic acid present in the cell wall. Instead, it is classified based on its 16S rRNA gene sequence and other phenotypic characteristics.

**Clinical Pearl / High-Yield Fact**
E. faecalis is a nosocomial pathogen that can cause a variety of infections, including urinary tract infections, endocarditis, and bacteremia. Its ability to grow in high-salt environments and resist heat makes it a challenging organism to eradicate from medical equipment and surfaces.

**✓ Correct Answer: A. Growns in 6.5% Nacl solution**